"It's in their genes" is a common refrain from scientists when asked about factors that allow centenarians to reach age 100 and beyond. Up until now, research has focused on genetic variations that offer a physiological advantage such as high levels of HDL ("good") cholesterol. But researchers at Albert Einstein College of Medicine and Ferkauf Graduate School of Psychology of Yeshiva University have found that personality traits like being outgoing, optimistic, easygoing, and enjoying laughter as well as staying engaged in activities may also be part of the longevity genes mix.